Method of making diamond tools



Sept. 16, 1941. R. H. TAYLOR- MBTHOD OF MAKING DIAMOND TOOLS 5 Sheets-Sheet 1 Filed April 9, 1940 INVENTOR Sept. 16, 1941. R. H. TAYLOR METHOD OFMAKING DIAMOND TOOLS Filed April 9, 1940 3 Sheets-Sheet 2 ATTORNEYS "Sept. 16, 1941. R. H. TAYLOR 2,256,062

\ METHOD OF MAKING DIAMOND TOOLS 'Filed April 9, 1940 3' Sheets-Sheet 3 1 I In".

INVENTO IUIHIIIL II V? n I A /2 I, a 7 1 v ATTORNEY v Patented Sept. 16, 1941 Rutherford to J. K. Smit &

H. Taylor, Millburn, N. J., asslgnor Sons, Inc., New York, N. Y., a

corporation of New York Application April 9, 1940, Serial No. 328,640

3 Claims My invention relates to a new and improved method and apparatus for the casting of diamond tools, particularly core bits, wherein the diamonds are embedded or set'in a metal matrix and function as the attrition or cutting medium.

One of the objects of my invention is the provision of an improved method and ap aratus whereby amore satisfactory tool is produced than is possible by some prior methods now in use in that I obtain a denser and more uniform matrix and a matrix free of blowholes, all of which promotes better retention of the diamonds in the matrix, a more uniform wear and longer useful life. Provision is made also for performing the casting operation in. an inert atmosphere which prevents injury to the skin of the diamonds.

More specifically my invention provides a method and apparatus wherein during the casting operation themold is slowly rotated on its own axis to provide for uniform distribution of the molten metal of the matrix.

Generally speaking, a common method of making diamond core bits or for that matter other types of diamond tools such as plug bits, dressing tools, etc., the mold is disposed vertically with the diamonds arranged in the bottom of it. The molten metal which is to compose the matrix is simply poured into the top of the mold. A very skilled and careful" operator may pour the metal into the mold and properly distribute it'so that a fairly uniformly dense matrix is produced, but unfortunately all operators are not careful with the result that as the metal is poured' into the mold the same must flow around the bottom of the mold until the entire bottom of the mold is covered. Although the casting operation takes but. a very short time, nevertheless by'the time the mold bottom is fully covered the metal which first struck the mold has chilled somewhat so that it is not in the same condition as the metal which enters the mold later. As a consequence, therefore, there is often an area in the matrix having different characteristics from the restof the matrix. By the present invention, however, I slowly rotate the mold during the pouring operation so that this inherent defect in prior proccases is eliminated.

In addition to this valuable feature of my invention I also provide for casting in an inert atmosphere which eliminates injury to the diamonds in the casting operation in that the diamonds are enveloped in an inert gas 'so as to prevent reaction between the diamonds and the molten metal during the casting operation;

. have shown one embodiment. of my invention in the accompanying drawings, wherein:

Fig. 1 is an elevational view of one form which my apparatus may take; Fig. 2 is a sectional elevational view of my ap- .constitutes the bottom bottom member 48 is made in sections.

the sides of the mold.

Fig. 3 is an exploded view: and Fig. 4 is a bottom plan view of the steel shank to which the diamond bearing matrix is locked Extending through this support or bench 2 is a-hollow cylindrical member 4, provided at its lower end with a removable cap 6, in one side with an exhaust line 8 connected to exhaust fan l0, and at its top with an annular flange l2 resting upon the top of the bench 2.

Extending into the top of the hollow cylindriw cal member 4 is a bearing thimble [4 provided at its upper end with a peripheral flange. l6 which is set into a depression in the flange l2 of the member 4. The lower end of this bearing thimble I4 is threaded and receives a tubular member l8 by which the bearing is drawn into firm engagement with the flange l2 of the member 4. It will be noted that the member I8 ex provided with a common cover plate 32 which is secured by machine screws 34 to the flange l2.

Secured to the upper, face of the gear 28 i an annulus 36 which receives and supports a moldring 38, the latter being provided for the reception of an inverted cup-shaped member 40 which of the mold. This mold As illustrated it is made in four sections. The purpose of making the-mold bottom in sections is to facilitate removal of the tool after the casting operation has been completed. The mold sections are inserted in the rin place therein by screws 42. I

44 designates the tool shank which is Preformed, and'is' usually of steel. The matrix is to be cast to this shank. A bottom plan view of the tool shank is shown in Fig. 4 from which it will be seen that the face of the shank is provided with radially extending locking grooves 48. In the casting operation the molten metal is poured throu h. the shank into the mold and runs into these grooves to provide a lock between th matrix and the tool shank.

48 designates a ring. or annulus constituting This ring or annulus 48 is 38 and held rigidly in provided with a depression in its lower face which fits the top of the bottom member 40 of the mold. The ring 48 is provided with flange 50 extending inwardly radially of the ring and this flange is adapted to cooperate with the flange 52 of the tool shank 44, so that when the parts are assembled and the nut 54 is set up the tool shank and the mold ring 48 will be held rigidly to each other. The flange 50 is preferably provided with vents 5|.

It will be seen from the foregoing that all parts of the molding apparatus are so constructed that the several units making up the apparatus are necessarily properly aligned when the parts are assembled. It will be evident also that the finished tool may be quickly removed after the casting operation.

56 designates a post mounted offset with respect to the mold structure. This post carries a bracket 58 adapted to be moved vertically of the post 56 and also to be swung thereon. This bracket 58 carries a gas ring 60 which may be integral therewith, and this ring, when the apparatus is in operation, is to be swung over the tool shank and mold, as shown in Fig. 2. This ring is undercut as shown at 6| for centering purposes. The ring 60 carries another ring 52 which may be termed a valve ring inasmuch as its function in addition to being a, pouring lip for the mold is to regulate the flow of an inert gas to the mold, the gasbeing supplied to the ri'ng'56 from a gas flask 64. The valve ring screws into the gas ring and by varying the setting of the ring 62 the space 63 between the adjacent faces of the members 62 and 60 can be. varied so as to vary the. volume of gas flowing through this space to the mold.

- In operation the bottom mold sections 50 are assembled in the mold ring 38 and secured in place therein by the screws 42. The diamonds are then positioned in the orifices 66 in the mold sections and may be temporarily secured thereto, if desired,by-atomizing a suitable adhesive ing stationary, and with the mold rotating molten metal is poured into the top of the apparatus through the tool shank to and upon the diamonds at the mold bottom, the passing of inert gas through the mold being continued during the pouring-operation.- It will be appreciated, of

' course, as above explained, that the cast matrix thus formed is locked to the tool shank in the casting operation. It will be understood that on each casting operation some bits of metal may pass the diamonds and are caught in the receptacle 4 from which they may be salvaged from time to time.

It will be seen fromall of the foregoing that I t have provided a very simple and practicable mold construction wherein the equipment may be very quickly set up for casting and wherein the completed tool may be quickly and easily removed.

good castings because of rotating the mold on its own axis, whereby proper disposition of the molten metal in the mold is provided for without relying upon the skill of the operator.

It is to be understood that changes may be made in the details of construction and arrange-, ment of parts within the purview of myinvention. What I claim is:

1. In the manufacture of diamond tools such as core bits, the method which comprises positioning diamonds in the form of an annulus in the perforations in the horizontally disposed bottom of a mold, placing a hollow tool shank in vertical position above said mold bottom with the lower end of the shank adjacent said diamonds, and while rotating the assemblyabout the vertical axis of the mold and shank pouring molten metal through the tool shank and out through the side walls thereof adjacent its lower end to on the same, such as collodion, for instance.

The carbon disc or core 68 is then placed in the bottom of the mold'as shown in Fig. 2. Thetool shank 44 is placed in position on top of the core piece 68, and the ring 48 slipped in place withthe post 56 until it is positioned on the ring 48 constituting the sides of the mold. The valve ring 62 has previously been adjusted or may be adjusted at this time so as to give the proper opening between 62 and 80.

The valve 10 which controls the flow of gas such as nitrogen, for instance, or other inert gas from the flask or bottle 64 is now opened and the blower or exhaust fan 10 started in operation so as to cause the inert gas to pass through the mold past the diamonds-in the orifices 66 in the mold and out through theexhaust line 8. It will be noted that the member I8 in the receptacle 4 extends beyond the mouth of the exhaust line 8 so as to promote passage of the inert gas through the mold, gear, etc.

The mold is now rotated at very, slow speed,

the mold bottom.

2. In the manufacture of diamond tools such as core hits, the method which comprises positioning diamonds in the perforations in the horizontally disposed bottom of a mold, placing a tool shank in vertical-position above the mold bottom ,with the lower end of the shankadjacent said diamonds, and while introducing an inert gas into the mold about the exterior shank and thence about'the diamonds and while rotating the assembly about the vertical axis of the mold.

and shank pouring molten metal vertically into the mold and diverting the same so that it flows practically horizontally about the diamonds and the end of the tool shank, thereby to embed the diamonds in a metal matrix which is united to the tool shank.

3. In the manufacture of diamond tools such as core bits, the method which comprises supporting a hollow tool shank in vertical position above a horizontally disposed mold bottom on which diamonds have been positioned, the lower end of the tool shank being maintained out of contact with the diamonds, and while rotatingthe mold and tool shank about their vertical axes pouring metal into the mold through said tool shank upon the pre positioned diamonds, the

speed of rotation of the mold and shank being so low that there is no substantial lateral movement of the molten metal under the action of centrifugal force.

' RUTHERFORD H. TAYLOR. 

